• Title, Summary, Keyword: soil-structure interaction

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Shaking table test on soil-structure interaction system (2) : Superstructure with foundation on layered soil (건물-지반 시스템에 관한 진동대실험 (2) : 성층지반위의 구조물)

  • Lee Sung-Kyung;Masato Motosaka;Min Kyung-Won
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.529-537
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    • 2005
  • This paper proposes the shaking table testing method, without any soil specimen only using building model as an experimental part, considering dynamic soil-structure interaction based on the substructure method. The two-layered soil is assumed as a soil model of the entire soil-structure interaction syhstem(SSI) in this paper. Differently from the constant soil stiffness, the frequency-dependent dynamic soil stiffness is approximated for the case of both acceleration and velocity feedback, respectively. The interaction force is observed from measuring the accelerations at superstructure. Using the soil filters corresponding to the approximated dynamic soil stiffness, the shaking table drives the acceleration or velocity, which the needed motion to give the building specimen the SSI effects. Experimental results show the applicability the proposed methodologies to the shaking table test considering dynamic soil-structure interaction.

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Seismic Fragility Evaluation of Isolated NPP Containment Structure Considering Soil-Structure Interaction Effect (지반-구조물 상호작용 효과를 고려한 지진격리시스템이 적용된 원전 격납건물의 지진 취약도 평가)

  • Eem, Seung Hyun;Jung, Hyung Jo;Kim, Min Kyu;Choi, In Kil
    • Journal of the Earthquake Engineering Society of Korea
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    • v.17 no.2
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    • pp.53-59
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    • 2013
  • Several researches have been studied to enhance the seismic performance of nuclear power plants (NPPs) by application of seismic isolation. If a seismic base isolation system is applied to NPPs, seismic performance of nuclear power plants should be reevaluated considering the soil-structure interaction effect. The seismic fragility analysis method has been used as a quantitative seismic safety evaluation method for the NPP structures and equipment. In this study, the seismic performance of an isolated NPP is evaluated by seismic fragility curves considering the soil-structure interaction effect. The designed seismic isolation is introduced to a containment building of Shin-Kori NPP which is KSNP (Korean Standard Nuclear Power Plant), to improve its seismic performance. The seismic analysis is performed considering the soil-structure interaction effect by using the linearized model of seismic isolation with SASSI (System for Analysis of Soil-Structure Interaction) program. Finally, the seismic fragility is evaluated based on soil-isolation-structure interaction analysis results.

Overstrength factors for SDOF and MDOF systems with soil structure interaction

  • Aydemir, Muberra Eser;Aydemir, Cem
    • Earthquakes and Structures
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    • v.10 no.6
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    • pp.1273-1289
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    • 2016
  • This paper addresses the concept of lateral overstrength; the ratio of actual lateral strength to design base shear force, for both SDOF and MDOF systems considering soil structure interaction. Overstrength factors are obtained with inelastic time history analysis for SDOF systems for period range of 0.1-3.0 s, five different aspect ratios (h/r=1, 2, 3, 4, 5) and five levels of ductility (${\mu}$=2, 3, 4, 5, 6) considering soil structure interaction. Structural overstrength for MDOF systems are obtained with inelastic time history collapse analysis for sample 1, 3, 6, 9, 12 and 15 storey RC frame systems. In analyses, 64 ground motions recorded on different site conditions such as rock, stiff soil, soft soil and very soft soil are used. Also lateral overstrength ratios considering soil structure interaction are compared with those calculated for fixed-base cases.

Shaking Table Testing Method Considering the Dynamic Soil-Structure Interaction (건물과 지반의 동적상호작용을 고려한 진동대 실험법에 관한 연구)

  • Lee, Sung-Kyung;Lee, Sang-Hyun;Chung, Lang
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.184-191
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    • 2010
  • This paper proposes the shaking table testing method for replicating the dynamic behavior of soil-structure interaction (SSI) system, without any physical soil model and only using superstructure model. Applying original SSI system to the substructure method produces two substructures; superstructure and soil model corresponding to experimental and numerical substructures, respectively. Interaction force acting on interface between the two substructures is observed from measuring the accelerations of superstructure, and the interface acceleration or velocity, which is the needed motion for replicating the dynamic behavior of original SSI system, is calculated from the numerical substructure reflecting the dynamic soil stiffness of soil model. Superstructure is excited by the shaking table with the motion of interface acceleration or velocity. Analyzing experimental results in time and frequency domains show the applicability the proposed methodologies to the shaking table test considering dynamic soil-structure interaction.

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Plastic hinge length of RC columns considering soil-structure interaction

  • Mortezaei, Alireza
    • Earthquakes and Structures
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    • v.5 no.6
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    • pp.679-702
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    • 2013
  • During an earthquake, soils filter and send out the shaking to the building and simultaneously it has the role of bearing the building vibrations and transmitting them back to the ground. In other words, the ground and the building interact with each other. Hence, soil-structure interaction (SSI) is a key parameter that affects the performance of buildings during the earthquakes and is worth to be taken into consideration. Columns are one of the most crucial elements in RC buildings that play an important role in stability of the building and must be able to dissipate energy under seismic loads. Recent earthquakes showed that formation of plastic hinges in columns is still possible as a result of strong ground motion, despite the application of strong column-weak beam concept, as recommended by various design codes. Energy is dissipated through the plastic deformation of specific zones at the end of a member without affecting the rest of the structure. The formation of a plastic hinge in an RC column in regions that experience inelastic actions depends on the column details as well as soil-structure interaction (SSI). In this paper, 854 different scenarios have been analyzed by inelastic time-history analyses to predict the nonlinear behavior of RC columns considering soil-structure interaction (SSI). The effects of axial load, height over depth ratio, main period of soil and structure as well as different characteristics of earthquakes, are evaluated analytically by finite element methods and the results are compared with corresponding experimental data. Findings from this study provide a simple expression to estimate plastic hinge length of RC columns including soil-structure interaction.

A new way to design and construct a laminar box for studying structure-foundation-soil interaction

  • Qin, X.;Cheung, W.M.;Chouw, N.
    • Earthquakes and Structures
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    • v.17 no.5
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    • pp.521-532
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    • 2019
  • This paper describes the construction of a laminar box for simulating the earthquake response of soil and structures. The confinement of soil in the transverse direction does not rely on the laminar frame but is instead achieved by two acrylic glass walls. These walls allow the behaviour of soil during an earthquake to be directly observed in future study. The laminar box was used to study the response of soil with structure-footing-soil interaction (SFSI). A single degree-of-freedom (SDOF) structure and a rigid structure, both free standing on the soil, were utilised. The total mass and footing size of the SDOF and rigid structures were the same. The results show that SFSI considering the SDOF structure can affect the soil surface movements and acceleration of the soil at different depths. The acceleration developed at the footing of the SDOF structure is also different from the surface acceleration of free-field soil.

Soil-Structure Interaction Analysis Method in Time Domain considering Near-Field Nonlinearity (근역지반의 비선형성을 고려한 시간영역 지반-구조물 상호작용 해석기법의 개발)

  • 김문겸;임윤묵;김태욱;박정열
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.309-314
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    • 2001
  • In this study, the nonlinear soil structure interaction analysis method based on finite element and boundary element method is developed. In the seismic region, the nonlinearity of near field soil has to be considered for more exact reflection of soil-structure interaction effect. Thus, nonlinear finite element program coupled with boundary elements is developed for nonlinear soil-structure interaction analysis. Using the developed numerical algorithm, the nonlinear soil-structure interaction analysis is performed and responses due to dynamic forces and seismic excitation are investigated. The developed method is verified by comparing with previous studies.

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Soil structure interaction effects on strength reduction factors

  • Eser, Muberra;Aydemir, Cem;Ekiz, Lbrahim
    • Structural Engineering and Mechanics
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    • v.41 no.3
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    • pp.365-378
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    • 2012
  • In this study, strength reduction factors are investigated for SDOF systems with period range of 0.1-3.0 s with elastoplastic behavior considering soil structure interaction for 64 different earthquake motions recorded on different site conditions such as rock, stiff soil, soft soil and very soft soil. Soil structure interacting systems are modeled and analyzed with effective period, effective damping and effective ductility values differing from fixed-base case. For inelastic time history analyses, Newmark method for step by step time integration was adapted in an in-house computer program. Results are compared with those calculated for fixed-base case. A new equation is proposed for strength reduction factor of interacting system as a function of structural period of system (T), ductility ratio (${\mu}$) and period lengthening ratio (T/T). It is concluded that soil structure interaction reduces the strength reduction factors for soft soils, therefore, using the fixed-base strength reduction factors for interacting systems lead to non-conservative design forces.

The effect of soil-structure interaction on inelastic displacement ratio of structures

  • Eser, Muberra;Aydemir, Cem
    • Structural Engineering and Mechanics
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    • v.39 no.5
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    • pp.683-701
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    • 2011
  • In this study, inelastic displacement ratios and ductility demands are investigated for SDOF systems with period range of 0.1-3.0 s. with elastoplastic behavior considering soil structure interaction. Earthquake motions recorded on different site conditions such as rock, stiff soil, soft soil and very soft soil are used in analyses. Soil structure interacting systems are modeled with effective period, effective damping and effective ductility values differing from fixed-base case. For inelastic time history analyses, Newmark method for step by step time integration was adapted in an in-house computer program. Results are compared with those calculated for fixed-base case. A new equation is proposed for inelastic displacement ratio of interacting system ($\tilde{C}_R$) as a function of structural period of interacting system ($\tilde{T}$), strength reduction factor (R) and period lengthening ratio ($\tilde{T}/T$). The proposed equation for $\tilde{C}_R$ which takes the soil-structure interaction into account should be useful in estimating the inelastic deformation of existing structures with known lateral strength.

Seismic analysis of frame-strap footing-nonlinear soil system to study column forces

  • Garg, Vivek;Hora, Manjeet S.
    • Structural Engineering and Mechanics
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    • v.46 no.5
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    • pp.645-672
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    • 2013
  • The differential settlements and rotations among footings cannot be avoided when the frame-footing-soil system is subjected to seismic/dynamic loading. Also, there may be a situation where column(s) of a building are located near adjoining property line causes eccentric loading on foundation system. The strap beams may be provided to control the rotation of the footings within permissible limits caused due to such eccentric loading. In the present work, the seismic interaction analysis of a three-bay three-storey, space frame-footing-strap beam-soil system is carried out to investigate the interaction behavior using finite element software (ANSYS). The RCC structure and their foundation are assumed to behave in linear manner while the supporting soil mass is treated as nonlinear elastic material. The seismic interaction analyses of space frame-isolated footing-soil and space frame-strap footing-soil systems are carried out to evaluate the forces in the columns. The results indicate that the bending moments of very high magnitude are induced at column bases resting on eccentric footing of frame-isolated footing-soil interaction system. However, use of strap beams controls these moments quite effectively. The soil-structure interaction effect causes significant redistribution of column forces compared to non-interaction analysis. The axial forces in the columns are distributed more uniformly when the interaction effects are considered in the analysis.